Reliable information on the demographics of mental retardation in America is almost completely lacking before the 1920's. Despite the contemporary interest in deinstitutionalization, there is little baseline data from previous normalization programs. This project--the first demographic history of mental retardation in America--will provide solid descriptive and analytical benchmarks for mental health practitioners and social scientists. The chief data source will be the records of 30,000 institutionalized retardates from ten states in the period 1851-1915. Using the newly developed method of Soundex Linkage, these records will be supplemented with the manuscript Federal census. Analysis will focus on community and family antecendents of retardates, institutional operations and policy, and the integration of the retardate to family and/or community. The resulting data sets will be available to qualified personnel for secondary re-analysis.